pH Sensor Flange Sealing for Bioreactor Sterilization
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Solution Overview
Problem
Existing pH measurement systems in fermentation and cell culture processes face challenges due to the need for sterilization of bioreactors and pH sensors, which can lead to sensor damage from high temperatures and rapid thermal shock, and require complex cleaning processes to remove residual buffer chemicals.
Innovation Solution
A pH sensing bioreaction system with a pH sensor attached to a plastic wall of a bioreactor, featuring a flange for permanent sealing, a reference electrolyte, and a mechanism to switch between a booted and service configuration, allowing protection during sterilization and exposure during operation, with a removable endcap for integration with additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pH sensor is sterilized along with the bioreactor using high temperature and steam, then the bioreactor is properly sterilized, but the sensor's life is significantly reduced due to thermal shock and high temperature exposure
Solution Approach 1:
The system divides the sterilization process into two separate segments: the bioreactor is sterilized independently using high temperature and steam, while the pH sensor is protected from these harsh conditions. The sensor can be sterilized separately using gentler methods or pre-sterilized before installation, thus resolving the contradiction between achieving effective bioreactor sterilization and preserving sensor lifespan.
Solution Approach 2:
A sterile barrier or interface is introduced between the sterilization process and the sensor. The bioreactor can be sterilized through its wall or port while the sensor remains protected behind this barrier. The barrier acts as an intermediary that allows sterilization of the bioreactor environment without exposing the sensor to damaging high temperatures and steam.
2Measurement precision
If the pH sensor undergoes two point calibration using buffer solutions, then measurement accuracy is improved, but residual buffer chemicals must be removed through complex cleaning processes including steaming
Solution Approach 1:
The calibration function is extracted from the main bioreactor system. The pH sensor can be calibrated externally using buffer solutions before installation, and then installed into the bioreactor as a pre-calibrated unit. This eliminates the need for complex in-situ cleaning processes within the bioreactor, as calibration is performed separately and the sensor is ready for immediate use after installation.
Solution Approach 2:
The system employs a disposable pH sensor that is pre-calibrated and pre-sterilized. After use, the sensor is discarded rather than cleaned and recalibrated. This eliminates the complex cleaning processes entirely, as each sensor is designed for single use, thereby resolving the contradiction between maintaining measurement precision and avoiding complex cleaning procedures.
3Stability of the object's composition
If the pH sensor is permanently attached to the bioreactor wall, then sensor stability and positioning are improved, but the sensor cannot be easily removed or replaced for maintenance or calibration
Solution Approach 1:
The mounting system transitions from a static permanent attachment to a dynamic reversible connection. The sensor is attached to the bioreactor wall using a mechanism that provides stable positioning during operation but allows easy removal when needed. Examples include bayonet-style connectors, bayonet-style connectors, or threaded fittings that can be quickly engaged and disengaged, thus resolving the contradiction between maintaining stable sensor positioning and enabling easy sensor replacement for maintenance or calibration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides a durable and efficient pH measurement solution that withstands sterilization processes and maintains accuracy by protecting the sensor during sterilization and allowing direct contact with the sample during operation, reducing the need for complex cleaning and extending sensor lifespan.
Implementation Method 1
The flange is configured to permanently and sealingly attach to the plastic wall
Implementation Method 2
pH is a measure of a relative amount of hydrogen and hydroxide ions in an aqueous solution
Implementation Method 3
Such cleaning can include steaming the fermenter or bioreactor as well as the pH sensor. Exposure to high temperatures, steam and rapid thermal shock
Data Source
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AI summary
A pH sensing bioreaction system is provided. The system includes a bioreaction container having a plastic wall and a pH sensor attached to the plastic wall. The pH sensor includes a sensor body having a flange that is sealingly attached to the plastic wall. The sensor body has a reference electrolyte therein and a first sensing element disposed in the reference electrolyte. The first sensing element is configured to contact both the reference electrolyte and a sample solution inside the bioreaction container. A second sensing element is positionable into an interior of the bioreaction container. The pH sensor has a plurality of configurations that include a booted configuration in which at least one sensing element is isolated from the interior of the bioreaction container, and a service configuration in which the at least one sensing element is fluidically coupled to the interior of the bioreaction container.